slide1 l.
Skip this Video
Download Presentation
Interactive Visualization of Intercluster Galaxy Structures in the Horologium-Reticulum Supercluster

Loading in 2 Seconds...

play fullscreen
1 / 21

Interactive Visualization of Intercluster Galaxy Structures in the Horologium-Reticulum Supercluster - PowerPoint PPT Presentation

  • Uploaded on

Jameson Miller UNC Chapel Hill. Cory W. Quammen UNC Chapel Hill. Interactive Visualization of Intercluster Galaxy Structures in the Horologium-Reticulum Supercluster. Matthew C. Fleenor Roanoke College. Data description. Galaxy positions in RA-DEC-cz coordinate system

I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
Download Presentation

PowerPoint Slideshow about 'Interactive Visualization of Intercluster Galaxy Structures in the Horologium-Reticulum Supercluster' - chinue

Download Now An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.

- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript

Jameson Miller

UNC Chapel Hill

Cory W. QuammenUNC Chapel Hill

Interactive Visualization of Intercluster Galaxy Structures in the Horologium-Reticulum Supercluster

Matthew C. FleenorRoanoke College

data description
Data description
  • Galaxy positions in RA-DEC-cz coordinate system
    • Right-ascension (RA) ~ longitude
    • Declination (DEC) ~ latitude
    • cz – radial dimension (recessional velocity)
  • ~2500 galaxy locations
  • ~30 clusters
domain questions
Domain questions
  • What is the distribution of intercluster galaxies?
  • Are there large void regions? How many?
  • Does the supercluster have filaments?
  • How do clusters fit into the structure defined by intercluster galaxies?
prior 3d experience
Prior 3D experience
  • Collaborators viewed data in immersive environment
  • Got lost – no context
previous interactive tools
Previous interactive tools
  • Cosmic Explorer [Song1993]
  • SGI Explorer [Christensen1995]
  • PartiView [Levy2001]
  • AstroMD [Gheller2002]
what s missing
What’s missing
  • Ability to group galaxies into structures they define
    • Voids
    • Filaments
  • Reference axes in all three RA-DEC-cz dimensions
data types
Data types
  • Sparse 3D position data
  • Nominal (categorical) data
    • Intercluster galaxies vs. clusters
    • User-defined groups indicating structure (filament, void boundary)

Group 1

Group 2



nominal encoding
Nominal encoding
  • 3D glyphs
    • Enough screen real estate
    • Distinct shapes encode object type
    • Depth queues from perspective and occlusion
  • Nominal color encoding
    • Group membership
    • Encoded by 10 of 12 colors recommended by Ware2004
ra dec cz reference axes
RA-DEC-cz reference axes
  • Orientation to dataset
  • Colored with just-noticeably-different color than background
  • Can turn sides, top, and bottom on or off
curved drop lines
Curved drop lines
  • Explicit connection between galaxies and reference axes
  • Curved to fit RA-DEC-cz coordinate system
  • Allows comparison to standard plots
structure perception
Structure perception
  • Structure-from-motion
    • Strongest shape cue
  • Torsional rocking
    • Structure-from-motion without interaction
  • Stereo
    • Complements other techniques
    • User can control eye-separation parameter
confirmation of analysis
Confirmation of analysis
  • Quantitative analysis shows two separate overdensities
  • Overdensities pop out in visualization
  • ~95% correspondence between grouping by hand and quantitative grouping
positive result
Positive result
  • Quick identification of void regions
  • Selection of galaxies along rim defines bounds of void
  • Offline sphere-fitting refines estimation
  • Six voids identified
  • Known clusters reside around voids
negative result
Negative result
  • Previous 2D plots identified potential filament structure
  • When rotated in 3D, filament is shown to be two separate structures
computation vs visualization
Computation vs. visualization
  • Voids – could compute
  • Filaments – maybe could compute
  • Visualization helps astronomers know where to focus quantitative analysis
effective techniques
Effective techniques
  • User-controlled interaction
    • Critical for maintaining viewer orientation
    • Interactive scaling allows snapping between overview of data and local features, giving context when zooming in
    • Home key moves back to a familiar orientation
  • Torsional rocking
    • Rocking aids void definition when far galaxies peek out from closer galaxy
    • View angle optimization
  • Stereo
    • Stereo is helpful for finding galaxies bordering voids
    • Picking with mouse was hampered by stereo
    • Collaborators came across campus to use it!
  • Called GyVe (GalaxyViewer)
  • Built on VTK, Python, and Tkinter
  • Available at
  • Runs on Windows and Linux
future work
Future work
  • Isosurfaces – initial attempt unused
  • Image processing for identifying voids from density projections
  • Add interactive statistical tools
  • Haptic probes to feel around for structures
  • NSF Grant AST 04-06443 (Fleenor)
  • James A. Rose
  • Russell M. Taylor II